A pair of sauropod verts

[pachy-pleuro-whatnot-odon]

Hi Paul,

 

On 1/26/2021 at 11:32 AM, paulgdls said:

Yes, it was a bit embarrassing as the person complaining was the head of collections! Mind you, when I was in Cairo a couple of years ago  I saw a man carrying the Naqada plaque in his hands, having just unscrewed a cabinet to move material to the new mega museum. I asked him how much he wanted for it and he said $10M dollars. Such is the Egyptian way of doing things. 

Yeah, the Dutch, I believe, are also somewhat more relaxed about their archaeological materials and digs, when compared to the British way of doing things. Of course we value our heritage greatly - I remember the National Museum of Antiquities making a big point about the way students had handled their artefacts in the "ancient materials"-class the year before ours - but, at the same time, I believe we Dutch are not as meticulous as you are across the Channel...

 

On 1/26/2021 at 11:32 AM, paulgdls said:

Interesting about your studies in student days. Did you handle any Neanderthal material?

Unfortunately not, though it would have been interesting and I have handled human remains. My main interest within the field of archaeology, however, is with Native American cultures - primarily their iconography - with a focus on the Andes and Panama and field experience in the Caribbean.

 

On 1/26/2021 at 11:32 AM, paulgdls said:

Yes, the slope is a bit strange. There was some matrix in that area which could have led to crushing.

I don't know. To me matrix having led to crushing sounds like things being the wrong way round. Now I won't claim to be very knowledgable when it comes to geology, but I'd be surprised if one of the major geological processes (uplifting, faults, etc.) would have led to such localised deformation. Rather, it would seem to make more sense to me that the depression in the bone was present prior to deposition, and just got filled in with additional matrix.

 

On 1/26/2021 at 11:32 AM, paulgdls said:

I see what you mean about the similarity to a coracoid. I don't see a ridge leading backwards from the articulation on any of these coracoids though. It was the distinctive ridge that made me think Scapula in the first place (the so called ventral ridge).

On 1/12/2021 at 5:41 PM, paulgdls said:

See, for me what you originally identified as a ventral ridge doesn't convince me of your piece being a scapula any more. Though there seemed to be some initial similarities between the P. rossicus scapula and your specimen, for me this has fallen apart with the removal of more matrix. Simply put, your specimen has bone in places where I wouldn't expect any if the piece were a scapula. I've updated my previously "annotated" version of the P. rossicus scapula to show where your specimen has bone I wouldn't expect (red line = break, indicated as articular surface in your diagram; red surface = unexpected bone). I've also come to realise that part of the reason why this is, is likely that we're looking at your find from different angles.

 

 

That is to say, reviewing Tarlo's (1960) schematics for pliosaur scapulae (figured again below, now including the variations listed more towards the end of his treatise), it appears the dorsal process is consistently considered the extension of bone that runs perpendicular to the main part of the scapula - the part that is formed by the bar of bone, between and in between, the glenoid ramus and ventral plate. I'll henceforth refer to the later as "the scapular bar".
 

 

If I compare these drawings to the scapulae of P. philarchus (also refigured below), I find that these match the given configuration quite well. What you've marked as "dorsal process" in your diagram, however, to me correlates much more to (part of) the scapular bar than to how Tarlo defines it: partially because of morphology (smooth, straight and flaring), and in part because the dorsal process doesn't have any bone perpendicular to it (i.e., above or below in Tarlo's diagrams), other than where it connects to the scapular bar. This, I hope, explains why the mentioned additional bone in your specimen, for me, rules out the possibility of the piece being a pliosaur scapula.

 

For, even if I were to consider what you've marked as "dorsal process" in your diagram as (part of) the scapular bar, then the bone directly next to it - that is, the attachment for the dorsal process, as well as the start of the process itself - would, in most pliosaur species, be offset to it with a sharp difference in height, appearing much like a drop so sharp as that in certain species the bone would seem to fold in on itself (as can be seen in P. philarchus or reconstructed L. ferox from Tübingen below). And while I concede that the bone immediately next to your "dorsal process" is indeed somewhat lower, I think, in this case, the surface would be sizeable enough to attribute it to geological compressional forces.

 

 

On 1/26/2021 at 11:32 AM, paulgdls said:

P.S. this is an attempt I made to match the bone against the type specimens of L. ferox and S. vorax:

 

I'm afraid your drawings don't help me too much either, as in the comparison with the S. vorax scapula your find is still covered by significant amounts of matrix, while in the case of L. ferox your specimen has a bony outgrowth on top of it that I don't see in L. ferox (unless this is on the reverse, of course), and doesn't seem to fit too well...

 

On 1/26/2021 at 11:32 AM, paulgdls said:

 

Similarly, your friend's find, though impressive, unfortunately isn't particularly informative either. As this has been verified to be pliosaurian by Steve Etches I won't doubt that it is. But it seems to me that this scapula is missing its dorsal process, consisting of just the scapular bar (i.e., ventral plate and glenoid ramus), giving it a look much more akin to the scapula of a terrestrial animal than a pliosaur. That is, unless there are indications the dorsal process has broken off from the other side of it or, more likely, this specimen follows Tarlo's Stretosaurus scapular morphology, and the dorsal process would've attached to the break at the top right of the specimen. However, I don't see any direct correlation to your specimen here: at best what you've marked as "dorsal process" in your diagram could be a section of the curved edge on the right of your friend's sample. But, in that case, your find would indeed need to have come from a gigantically upscaled pliosaur... and following Ockam's Razor, I feel this is less likely than your fragment simply being a different bone altogether...

 

All of this having been said, I would like to reiterate my opinion that your specimen is reminiscent of a pliosaur coracoid. For one, and I know this is probably rather superficial, the area you've marked as "dorsal process", to me, doesn't look dissimilar to part of the coracoid my friend found (see images below for ease of comparison). Unfortunately, I don't know the exact size of the coracoid he found, but since, in the photographs, it's displayed on toilet paper of 10cm height, I think certain calculations can be made (will send you a separate PM to answer Steve's question).

 

On 1/11/2021 at 12:20 PM, paulgdls said:

On 1/23/2021 at 10:49 PM, pachy-pleuro-whatnot-odon said:

 

My greatest argument, however, hinges on your "dorsal process" being an articular surface between two coracoids, as well as presence of the bulging bony outgrowth on one side of your specimen. Ive therefore gone back to some of the photographs posted before and have tried to annotate them to highlight exactly this structure. even though I believe you already got what I meant before. I realise that these coracoids are normally a lot thinner. But seeing as I expect your specimen to mostly comprise the bulging part of the coracoid, I think the actual thickness of your find is difficult to estimate.

 

 

In any case, I'd say this is about as far as my knowledge currently reaches. I simply don't think I have the experience to help you out much beyond this. Seeing as you're obviously in touch with Steve Etches, have you asked Steve for his opinion on the piece yet?

 

Anyway, I hope this is still a helpful contribution to the discussion...

Cheers,

Alexander.

 

P.s.: sorry for taking so long to respond, but I wanted to make sure I got my thoughts straightened out and get the wording as best I could.